Olsson says they look much stronger as a unit but was quick to warn the club's fans that it will take time for them to fulfil their potential.
"I am not going to say anything bad about [former manager Steve] Kean, he was good in his way as well, but Berg was a legend when he was playing," Olsson told the Lancashire Telegraph.
"It is still very early, he has only been here a week, but he does a lot of tactics like working the whole team instead of the back four. It won't take a week to change but it is everyone together and I think it has been shown on the pitch."
The 24-year-old also expressed his delight at his recently-formed partnership with twin brother Markus.
"If Markus keeps getting the games and I keep playing we will get a partnership, it is good to play with him but it doesn't matter who we play with - we need to start winning games."